Reconfigurable wireless transmission system
A wireless transmission system supporting at least first and second high-isolation transmission modes. In the first TX mode, first and second incoming data streams are processed independently within first and second TX paths to generate first and second analog outgoing signals for separate transmission via first and second antennas. In the second TX mode, the two incoming data streams are combined to form a combined data stream. First and second versions of the combined data stream are processed by the first and second TX paths to generate two analog signals that are combined for transmission via a single antenna. In the second TX mode, a feedback signal, based on differences between the two analog signals, is used to adjust the relative phase and/or delay of the two versions of the combined signal in the digital domain to reduce phase differences between the two analog signals, thereby increasing signal transmission power.
1. A reconfigurable wireless transmission system comprising:
a digital processor adapted to receive at least first and second incoming data streams and generate at least first and second outgoing data streams;
a first transmission path adapted to receive the first outgoing data stream and generate a first analog output signal;
a second transmission path adapted to receive the second outgoing data stream and generate a second analog output signal;
a switching sub-system that enables the system to be configured in any one of at least first and second transmission modes, wherein:
in the first transmission mode, the first analog output signal is transmitted via a first antenna and the second analog output signal is transmitted via a second antenna; and
in the second transmission mode, the first and second analog output signals are combined for transmission via the first antenna; and
a feedback path connected to feed back a difference signal, corresponding to the first and second analog output signals, from the switching sub-system to the digital processor for use in controlling the second transmission mode.
2. The invention of claim 1 , wherein the system is further configurable in a third transmission mode, in which the first and second analog output signals are combined for transmission via the second antenna.
3. The invention of claim 1 , wherein the switching sub-system comprises:
a first switch having a first-switch input terminal connected to receive the first analog output signal and adapted to selectively apply the first analog output signal to either a first first-switch output terminal or a second first-switch output terminal;
a second switch having a first second-switch input terminal and a second second-switch input terminal and adapted to selectively apply an analog signal received at one of the first and second second-switch input terminals to a second-switch output terminal connected to the first antenna;
a third switch having a third-switch input terminal connected to receive the second analog output signal and adapted to selectively apply the second analog output signal to either a first third-switch output terminal or a second third-switch output terminal;
a fourth switch having a first fourth-switch input terminal and a second fourth-switch input terminal and adapted to selectively apply an analog signal received at one of the first and second fourth-switch input terminals to a fourth-switch output terminal connected to the second antenna;
a combiner having:
a first combiner input port connected to the second first-switch output terminal;
a second combiner input port connected to the second third-switch output terminal; and
a sum output port, wherein the combiner is adapted to combine analog signals received at the first and second combiner input ports and present an analog sum signal at the sum output port; and
a fifth switch having a fifth-switch input terminal connected to the first combiner output port and adapted to selectively present the analog sum signal at one of a first fifth-switch output terminal connected to the second fourth-switch input terminal and a second fifth-switch output terminal connected to the second second-switch input terminal.
4. The invention of claim 3 , wherein the combiner is a 3dB quadrature hybrid.
5. The invention of claim 3 , wherein:
the combiner further comprises a difference output port, wherein the combiner is adapted to difference the analog signals received at the first and second combiner input ports and present an analog difference signal at the difference output port; and
the feedback path is connected to receive and convert the analog difference signal into a digital feedback signal, wherein the digital processor is adapted to process the first and second incoming data streams based on the digital feedback signal.
6. The invention of claim 5 , wherein the feedback path comprises:
a detector adapted to generate an analog voltage signal representative of power of the analog difference signal; and
an analog-to-digital converter (ADC) adapted to digitize the analog voltage signal to generate the digital feedback signal.
7. The invention of claim 1 , wherein each of the first and second transmission paths comprises:
a digital-to-analog converter (DAC) adapted to convert the corresponding outgoing data stream into an analog baseband signal;
an upconverter adapted to upconvert the analog baseband signal to generate an analog radio-frequency (RF) signal;
a power amplifier adapted to amplify the analog RF signal to generate an amplified analog RF signal; and
a transmission filter adapted to filter the amplified analog RF signal to generate the corresponding analog output signal.
8. The invention of claim 1 , wherein:
in the first transmission mode:
the digital processor generates the first outgoing data stream based on the first incoming data stream, but independent of the second incoming data stream; and
the digital processor generates the second outgoing data stream based on the second incoming data stream, but independent of the first incoming data stream; and
in the second transmission mode:
the digital processor (i) combines the first and second incoming data streams to generate a combined data stream and (ii) generates both of the first and second outgoing data streams based on the combined data stream.
9. The invention of claim 8 , wherein, in the second transmission mode:
the digital processor adjusts at least one of phase and delay of a first version of the combined data stream to generate the first outgoing data stream; and
the digital processor adjusts at least one of phase and delay of a second version of the combined data stream to generate the second outgoing data stream.
10. The invention of claim 9 , wherein, in the second transmission mode, the digital processor adjusts the phase of the first and second versions of the combined data stream to reduce phase differences between the two analog signals combined by the combiner.
11. The invention of claim 9 , wherein, in the second transmission mode, the digital processor adjusts amplitude of the first and second versions of the combined data stream to generate the first and second outgoing data streams.
12. The invention of claim 9 , wherein, in the second transmission mode, the digital processor adjusts the at least one of phase and delay of the first and second versions of the combined data stream to generate the first and second outgoing data streams based on a digital feedback signal generated by a feedback path connected to the switching sub-system.
13. The invention of claim 1 , wherein the switching sub-system provides isolation such that, during the first transmission mode:
substantially none of the first analog output signal is transmitted via the second antenna; and
substantially none of the second analog output signal is transmitted via the first antenna.
14. A wireless transmission method comprising:
receiving at least first and second incoming data streams and generating at least first and second outgoing data streams;
receiving the first outgoing data stream and generating a first analog output signal;
receiving the second outgoing data stream and generating a second analog output signal;
selectively performing the method in any one of at least first and second transmission modes, wherein:
in the first transmission mode, the first analog output signal is transmitted via a first antenna and the second analog output signal is transmitted via a second antenna; and
in the second transmission mode, the first and second analog output signals are combined for transmission via the first antenna; and
feeding back a difference signal, corresponding to the first and second analog output signals, for use in controlling the second transmission mode.
15. A reconfigurable wireless transmission system comprising:
a digital processor adapted to receive at least first and second incoming data streams and generate at least first and second outgoing data streams;
a first transmission path adapted to receive the first outgoing data stream and generate a first analog output signal;
a second transmission path adapted to receive the second outgoing data stream and generate a second analog output signal;
a switching sub-system that enables the system to be configured in any one of at least first and second transmission modes, wherein:
in the first transmission mode, the first analog output signal is transmitted via a first antenna and the second analog output signal is transmitted via a second antenna;
in the second transmission mode, the first and second analog output signals are combined for transmission via the first antenna; and
the switching sub-system comprises:
a first switch having a first-switch input terminal connected to receive the first analog output signal and adapted to selectively apply the first analog output signal to either a first first-switch output terminal or a second first-switch output terminal;
a second switch having a first second-switch input terminal and a second second-switch input terminal and adapted to selectively apply an analog signal received at one of the first and second second-switch input terminals to a second-switch output terminal connected to the first antenna;
a third switch having a third-switch input terminal connected to receive the second analog output signal and adapted to selectively apply the second analog output signal to either a first third-switch output terminal or a second third-switch output terminal;
a fourth switch having a first fourth-switch input terminal and a second fourth-switch input terminal and adapted to selectively apply an analog signal received at one of the first and second fourth-switch input terminals to a fourth-switch output terminal connected to the second antenna;
a combiner having:
a first combiner input port connected to the second first-switch output terminal;
a second combiner input port connected to the second third-switch output terminal; and
a sum output port, wherein the combiner is adapted to combine analog signals received at the first and second combiner input ports and present an analog sum signal at the sum output port; and
a fifth switch having a fifth-switch input terminal connected to the first combiner output port and adapted to selectively present the analog sum signal at one of a first fifth-switch output terminal connected to the second fourth-switch input terminal and a second fifth-switch output terminal connected to the second second-switch input terminal.
16. The invention of claim 15 , wherein the combiner is a 3 dB quadrature hybrid.
17. The invention of claim 15 , wherein:
the combiner further comprises a difference output port, wherein the combiner is adapted to difference the analog signals received at the first and second combiner input ports and present an analog difference signal at the difference output port; and
the system further comprises a feedback path connected to receive and convert the analog difference signal into a digital feedback signal, wherein the digital processor is adapted to process the first and second incoming data streams based on the digital feedback signal.
18. The invention of claim 17 , wherein the feedback path comprises:
a detector adapted to generate an analog voltage signal representative of power of the analog difference signal; and
an analog-to-digital converter (ADC) adapted to digitize the analog voltage signal to generate the digital feedback signal.
19. A reconfigurable wireless transmission system comprising:
a digital processor adapted to receive at least first and second incoming data streams and generate at least first and second outgoing data streams;
a first transmission path adapted to receive the first outgoing data stream and generate a first analog output signal;
a second transmission path adapted to receive the second outgoing data stream and generate a second analog output signal;
a switching sub-system that enables the system to be configured in any one of at least first and second transmission modes, wherein:
in the first transmission mode, the first analog output signal is transmitted via a first antenna and the second analog output signal is transmitted via a second antenna;
in the second transmission mode, the first and second analog output signals are combined for transmission via the first antenna;
in the first transmission mode:
the digital processor generates the first outgoing data stream based on the first incoming data stream, but independent of the second incoming data stream; and
the digital processor generates the second outgoing data stream based on the second incoming data stream, but independent of the first incoming data stream; and
in the second transmission mode:
the digital processor (i) combines the first and second incoming data streams to generate a combined data stream and (ii) generates both of the first and second outgoing data streams based on the combined data stream.
20. The invention of claim 19 , wherein, in the second transmission mode:
the digital processor adjusts at least one of phase and delay of a first version of the combined data stream to generate the first outgoing data stream; and
the digital processor adjusts at least one of phase and delay of a second version of the combined data stream to generate the second outgoing data stream.
21. The invention of claim 20 , wherein, in the second transmission mode, the digital processor adjusts the phase of the first and second versions of the combined data stream to reduce phase differences between the two analog signals combined by the combiner.
22. The invention of claim 20 , wherein, in the second transmission mode, the digital processor adjusts amplitude of the first and second versions of the combined data stream to generate the first and second outgoing data streams.
23. The invention of claim 20 , wherein, in the second transmission mode, the digital processor adjusts the at least one of phase and delay of the first and second versions of the combined data stream to generate the first and second outgoing data streams based on a digital feedback signal generated by a feedback path connected to the switching sub-system.